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USB: serial: fix port tear down use-after-free

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Some drivers for multiport devices access port driver data from
completion handlers of shared URBs submitted at attach() or first open()
and stopped at disconnect() or last close(), respectively.

A simple NULL check before accessing the driver data makes sure that a
port state container has at least been allocated, but a completion
handler can still race with port tear down.

Reorder the disconnect handling so that ports are not deregistered (and
their driver data freed) until after all ports have been hung up and the
driver disconnect() callback has run so that all I/O has been stopped.

Fixes: 2d93148ab6 ("USB: serial: fix lifetime and locking problems")
Reported-by: syzbot+e5e28c3e953b2eebb16e@syzkaller.appspotmail.com
Link: https://lore.kernel.org/all/6a7e6fb9.ec5dc6cc.21cb3f.00c0.GAE@google.com/
Cc: stable@vger.kernel.org	# 2.6.30
Cc: Alan Stern <stern@rowland.harvard.edu>
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Johan Hovold <johan@kernel.org>
This commit is contained in:
Johan Hovold 2026-08-21 17:45:43 +02:00
parent b51faf3f2e
commit 33c920f7c5
1 changed files with 7 additions and 2 deletions
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9
drivers/usb/serial/usb-serial.c
View File

@ -1191,11 +1191,16 @@ static void usb_serial_disconnect(struct usb_interface *interface)
usb_serial_port_poison_urbs(port);
wake_up_interruptible(&port->port.delta_msr_wait);
cancel_work_sync(&port->work);
}
if (serial->type->disconnect)
serial->type->disconnect(serial);
for (i = 0; i < serial->num_ports; ++i) {
port = serial->port[i];
if (device_is_registered(&port->dev))
device_del(&port->dev);
}
if (serial->type->disconnect)
serial->type->disconnect(serial);
release_sibling(serial, interface);